Average Peak Age of Information Analysis for Wireless Powered Cooperative Networks
Abstract : Future of massive Internet-of-things (IoT) and low latency applications hinges on delivering fresh information on time. Thus, to analyse data freshness for time critical use cases in future networks, the age of information (AoI) measure is introduced. Besides, energy harvesting is also essential to improve energy sustainability and lifetime of a power-constrained and cost-efficient network. Therefore, we investigate a new network architecture suitable for future massive IoT where connectivity, energy sustainability and freshness of information are emerged. We study a wireless powered cooperative network, wherein a source and a relay charge their finite-sized capacitors by harvesting energy from a power station. For decode-and-forward (DF) and amplify-and-forward relaying strategies, average AoI and peak AoI (PAoI) are investigated to indicate how the randomness of the data/power transfer and size of the capacitors affect the age metrics. It is shown that, although utilizing a power-limited relay imposes more delay, the age metrics could be improved. Specifically, for the DF scheme with more waiting time due to signal processing, we may achieve lower average PAoI due to improving the reliability. Furthermore, special cases of the proposed system are discussed, e.g., full-power nodes and one-shot successful data transmission. Finally, numerical results are provided to clarify when a relaying strategy can outperform the direct transmissions. It is shown that for all values of the size of the capacitors, position of the relay, the power station’s power, and etc, there is not a unique optimal transmission strategy to minimize AoI metrics.
? It is also observed that there exists a unique optimal p such that the system average AoI achieves a minimum.
? Some interesting results are obtained, and there exists an optimal generating probability of sensor data (user) p such that the AoI reaches a minimum.
? AoI was shown to be a fundamentally novel metric of timeliness, significantly different, to existing ones such as delay and latency.
? Approaching information transmission in the context of timeliness gives rise to a number of problems where AoI can be considered as a concept to be incorporated in already existing communication systems.
? To investigate this issue, we assume a two-hop relay WPT-based system, wherein the source and relay are equipped with a finite-size capacitor and capture their required transmission powers from the received RF signal transmitted from a power station to charge them remotely.
? The timeliness of status updates was first investigated in the context of vehicular networks, where the authors addressed the broadcast problem.
? The problem of identifying the optimal sampling strategy of a communication system in relation to AoI, has attracted particular attention due to the connection it implies with estimation errors
• The performance of the proposed strategies that utilize only local CSI and REI is shown to be comparable to that of the optimal strategy that demands global CSI and REI.
• Many cooperation strategies have been proposed with different relaying techniques, such as amplify-and-forward (AF) and decode-and-forward (DF).
• Several power allocation strategies have been proposed to minimize the average transmission power for different cooperation schemes, system objectives and network topologies.
• The MRE and MEI strategies studied in this work was proposed and analyzed in for data gathering applications in sensor networks.
? In performance of multi-hop relay channels under two conventional amplify-and-forward (AF) and decode-and-forward (DF) schemes are compared.
? Moreover, policies that minimize the average AoI and the role of information source diversity on system performance are studied.
? It is well-known that utilizing a cooperative relay can improve the system performance, especially when the direct link between the source and the destination is not good enough.
? In addition, all special cases of the proposed system model are discussed, and the simplified results were presented to highlight the extreme performances of the general system model.
|